Process for producing wrinkle resistant carbamate-modified cellulosic textile materials by catalysis with hydrogen halide gas



United States Patent Office 3,518,044 Patented June 30, 1970 U.S. Cl.8-129 4 Claims ABSTRACT OF THE DISCLOSURE Cotton cellulosic materialsare impregnated with N- methylol type crosslinking agents, dried tonormal regain at about 60 C., and the reaction catalyzed with ananhydrous hydrogen halide gas at temperatures in the range of 28 to 65C., for periods of time in the range of 0.5 to 60 minutes.

A non-exclusive, irrevocable, royalty-free license in the inventionherin described, throughout the world for all purposes of the UnitedStates Government, with the power to grant sublicenses for suchpurposes, is hereby granted to the Government of the United States ofAmerica.

This application is a division of Ser. No. 668,973, filed Sept. 19,1967, now US. Pat. No. 3,450,485, which in turn is acontinuation-in-part of application Ser. No. 395,627, filed Sept. 10,1964, now abandoned.

This invention relates to treatments which impart wrinkle resistance tocellulosic textile materials. More particularly, it provides a processwhereby cellulosic textile materials may be impregnated with N-methyloltype crosslinking agents and then treated with gaseous hydrogen halidecatalyst to yield products exhibiting improved resiliency, wrinkleresistance, wash-Wear properties, and durable creases.

crosslinking cellulosic textile materials with -N- methylol typefinishing agents to produce dimensional stability and wrinkle resistanceis well known by those skilled in the art. However, industrial processesfor accomplishing this are almost invariably those in which the textilematerial is impregnated with a solution or emulsion containing thecrosslinking agent and an acidic or latent acidic catalyst compound, thetextile dried, and then cured by baking at high temperature, that is,about l40-l50 C. Other crosslinking processes utilizing N- methylolfinishing agents are those in which the cellulosic material iscrosslinked in the wet state by treatment with a solution of theN-methylol agent and acidic catalyst. To date, processes of this lattertype have not achieved widespread industrial usage.

Each of these crosslinking processes has some disadvantages which makedesirable the development of new processes to produce wrinkle resistanttextile materials.

A process wherein cellulose acetate or saponified cellulose acetate istreated by impregnating the cellulosic derivative with aurea-formaldehyde adduct, drying, and then exposing to the atmosphere inequilibrium with 36% aqueous hydrochloric acid, has been disclosed byDreyfus and Moncrietf in U.S. Pat. 2,235,141. This treatment providesonly a limited degree of improvement in resiliency when applied tocotton material and when agents other than urea-formaldehyde adducts areemployed. The improvement does not yield fabrics with a sufficient levelof wrinkle resistance for practical utility in wrinkle-resistant orwash-wear garments.

It is an object of the present invention to provide a new process forfinishing cellulosic textile materials with N-methylol type crosslinkingagents to produce improved resiliency, wrinkle resistance, both wet anddry, washwear properties, and durable creases.

By the process of this invention, this objective is achieved througheconomical operating conditions which involve the use of inexpensive,conventional N-methylol type crosslinking agents and gaseous hydrogenhalide catalysts, relatively low temperatures, and not unduly longreaction (or curing) times. The process essentially consists of thefollowing steps: (1) impregnating the cellulosic textile material with asolution, preferably aqueous, containing an N-methylol type crosslinkingagent, (2) drying, or evaporating the solvent, (3) treating theN-methylol crosslinking agent-containing cellulosic material withanhydrous hydrogen halide gas, such as hydrogen chloride, hydrogenbromide, and the like, to bring about reaction between the 'N-methylolagent and available cellulosic hydroxyl groups, and (4) washing thetreated material to remove unused reactant, catalyst, and byproducts.

In a preferred embodiment of the instant invention wherein cotton is thecellulosic material, dimethylol ethyl carbamate is the N-methylol typecrosslinking agent, and anhydrous hydrogen chloride gas is the catalyst,the process comprises the following steps for improving the wrinkleresistance and resiliency of, and imparting durable creases andwash-wear properties to cotton:

(a) Padding the cotton material with an aqueous solution containingabout from 7% to 15% by weight of dimethylol ethyl carbamate, anaminoplast creaseproofing and crosslinking agent,

(b) Drying the wet, impregnated cotton material from (a) at about 60 C.until the fibers of the said material contain about their normalmoisture regain value,

(c) Exposing the dry, impregnated cotton material from (b) to at least0.5%, based on the weight of the cotton material treated, of anhydroushydrogen chloride gas catalyst, for periods of time about from 0.5 to 60minutes, at temperatures about from 28 to 65 C., the longer periods oftime being employed with the lower temperatures, to catalyze thecrosslinking reaction between the crosslinking chemical agent and thecellulosic chains, and

(d) Removing the thus exposed cotton material from the hydrogen chloridegas atmosphere, neutralizing the residual catalyst and acidicby-products with a dilute aqueous alkaline solution, and water washingand drying the resulting chemically modified cellulosic cotton materialto remove unused reactants, residual catalyst, and by-products.

The reaction between N-methylol type finishing agents, which are used toimpart wrinkle resistance, and cellulosic textile materials is believedto proceed by a mechanism in which the cellulose chains are crosslinked.The uncatalyzed reaction is so slow that practically no reaction takesplace even upon reaction times of many months. With acidic catalysis,the reaction time can be shortened markedly. With a combination ofacidic catalysis and elevated temperature, as in conventionalpad-dry-cure finishing, reaction times of a minute or two, or even less,are possible. From practical considerations, however, speed of reactionmust be balanced against strength loss due to acidic hydrolysis of thecellulosic chains. The present invention in which gaseous hydrogenhalide catalysis is employed has the advantage that relatively lowtemperatures are operable without the necessity of impractically longcuring times. Furthermore, the utilization of relatively low curingtemperatures is conducive to preservation of good textile strength.

Crosslinkage of cellulosic chains brings about a number of importantchanges in properties. Among these are: improved wrinkle resistance,increased resiliency, improved dimensional stability (shrinkresistance), decreased tearing strength, reduced water absorption,reduced afiinity for direct dyes, improved rot resistance, andinsolubility in the usual cellulose solvents, such ascupraethylenediamine.

Products of the present invention, in general, exhibit the typicalcharacteristics of crosslinked cellulose. However, the degree of changeof some properties, as compared with the unmodified cellulosic startingmaterial, is often significantly less than that of other crosslinkingprocesses. For example, moisture regains of the products of the presentinvention are generally greater or only slightly lower than that of theuncrosslinked starting material. Products of other crosslinkingprocesses generally have markedly lower moisture regain values.

The commercial importance of a textile product with the propertiesimparted by crosslinking is obvious to those skilled in the art oftextile finishing. To obtain the property of wrinkle resistance, forexample, in the United States alone, approximately two billion yards ofcotton fabric were treated in 1961. A more satisfactory crosslinkingprocess could affect further increases in this already large productionfigure.

In addition to wrinkle resistance and wash-wear properties, durablecreases and pleats may be imparted to cellulosic textile materials bythe process of this invention. Creases and pleats are introduced, asdesired, in the N- methylol finishing agent-impregnated cellulosicmaterial which is then treated with anhydrous hydrogen halide gas whilein such configuration. The cellulose crosslinks produced by the reactionhold the textile in the creased configuration. The creases are durableto repeated laundering and wearing by the same mechanism which operatesto make fiat, smooth areas resistant to wrinkling and mussing.

As stated above, in the process of the present invention, cellulosictextile materials are impregnated with a solution of the N-methylolcrosslinking agent, the solvent removed, and the N-methylol crosslinkingagent-containing cellulosic material treated with anhydrous gaseoushydrogen halide to bring about chemical reaction between the cellulosichydroxyl groups and the N-methylol crosslinking agent. Adjustment of thevariables of the process determines the degree of reaction andproperties of the finished textiles. Among the variables which affectthe properties of the product are: nature of the cellulosic startingmaterial, pretreatments, fabric structure, nature and concentration ofN-methylol crosslinking agent employed, moisture content of theN-methylol agent-containing cellulosic material, nature andconcentration of gaseous hydrogen halide catalyst employed, time oftreatment, and temperature of treatment. The variables are interrelatedsuch that products with almost any desired degree of reaction, within anextremely broad range, can be produced by the process of the invention.

Fiber, yarn, or fabric may be treated; preferred treatment is carriedout on fabric. The fabric treated may be composed of cotton, regeneratedcellulose fiber, or etherified cellulosic fiber, and the like. Amongetherified cellulosic fibers which may be employed are cotton fiberschemically modified so as to bear an ether substitutent selected fromthe group consisting of methyl, ethyl, carboxymethyl, carboxyethyl,alpha-methyl carboxyrnethyl, phosphonomethyl, aminoethyl, hydroxyethyl,hydroxypropyl, carbamoylethyl, and sulfoethyl to a degree ofsubstitution (D.S.) of about from 0.01 to 0.25 ether radicals peranhydroglucose unit of the cellulose chain.

Fabrics composed of blends of any of these cellulosic fibers, andfabrics composed of blends of these fibers with other fibers also may betreated by the process of this invention. When cotton fabric is used asthe starting material, the fabric may be treated with the fibers in thenative state or in a prepared state, that is, the fabric may be scoured,kierboiled, desized, bleached, mercerized, or dyed, or may be subjectedto any combination of these pretreatment operations. Furthermore,cellulosic fibers which previously have been subjected to any treatmentstable to acid hydrolysis and which still have sites available forfurther reaction may be treated by the process of this invention.

Treatment of the cellulosic textile material with softeners, handmodifiers, and other additives prior to impregnation with the N-methylolcrosslinking agent or inclusion of such additives with the N-methylolcrosslinking agent in the impregnation bath is often beneficial.Pretreatment with emulsified polyethylene or application of polyethylenealong with the N-methylol agent, for example, results in a finishedfabric with higher tearing strength and higher Wet and dry (conditioned)crease recovery angles than cotton fabric treated similarly but withoutapplication of polyethylene.

N methylol crosslinking agents which may be used in carrying out theprocess of this invention include the N-methylol agents conventionallyused for imparting wrinkle resistance to cellulosic fabrics. Theseagents are monomers or relatively low molecular weight polymers, such asdimers or trimers, resulting from the condensation of formaldehyde andsuitable compounds bearing amide groups or groups of amidic character.Thus applicable in this invention are the ureaformaldehyde resins,including the methylol ureas and alkyl ethers, particularly methylethers of methylol ureas, the cyclic ureas, as for example,ethyleneurea, dihydroxyethyleneurea, propyleneurea, their formaldehydecondensates and alkylated derivatives, and the like, and formaldehydecondensates of monoalkyl carbamates, aliphatic polycarboxylic amides,triazones, triazines, and the like, and their alkylated derivatives.These agents may be employed singly, or in combination with one another,or in combination with other resins the presence of which does notadversely affect the process of this invention.

The N-methylol crosslinking agent may be applied to the cellulosictextile material by any of the techniques conventionally employed intextile wet processing. That is, the textile material may be immersed ina solution of N-tmethylol crosslinking agent, followed by passingthrough pad rolls or by centrifugation to remove excess solution, or maybe impregnated by spraying with a solution of the agent. A wet pickup ofthe N-methylol crosslinking agent solution by the cellulosic material ofabout from 50% to (of the weight of the textile) is recommended.Concentration of the N-methylol crosslinking agent in the solutionemployed may be varied about from 1% to 50% (of the weight of thesolution). The preferred range of concentration, however, includes aboutfrom 7% to 15%. N-methylol crosslinking agent solutions are most simplyand economically prepared and used as aqueous solutions. Other solvents,however, may be employed, if desired.

After impregnation of the textile with the solution of N-methylolcrosslinking agent, the water or other solvent used is removed by dryingor evaporating. Moisture content of the impregnated cellulosic fibers atthe time of the gaseous hydrogen halide treatment affects the rate andextent of reaction and thus the properties of the treated material. Bestresults are obtained when the fibers contain about their normal moistureregain value (about from 6% to 10% moisture). When the fibers containless than normal regain, the rate and extent of reaction are decreased;when completely dry, little or no reaction occurs. With moisturecontents above about 10%, the rate and extent of reaction decrease asthe moisture content is increased.

Hydrogen halide gases which may be employed in this invention includehydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogeniodide. Because of corrosion difiiculties, cost, availability, andmolecular weight considerations, hydrogen chloride and hydrogen bromideare preferred as gaseous catalysts and are employed as the anhydrousgases in the process of the present invention.

The concentration of hydrogen halide gas employed to catalyze thereaction may be varied from about 0.25% O.W.F. (percent by weight ofcatalyst based on weight of fabric treated) to about O.W.F. Thepreferred range of concentration includes about from 0.5% O.W.F. to 10%O.W.F. In general, the higher the catalyst concentration employed, thefaster the reaction of the N-methylol crosslinking agent with thecellulosic material and the shorter the treatment time necessary toachieve a given degree of wrinkle resistance.

The hydrogen halide treatment time necessary to carry out the process ofthis invention varies from a few seconds to about one hour. Thetreatment time employed in any given case is a function of the fabricproperties desired and of the temperature of the treatment and of theconcentration of catalyst used. In general, treatment time is adjustedinversely with temperature of treatment and catalyst concentration.Treatment times of about from 0.5 to 10 minutes are preferred, as theycan be utilized to produce high degrees of wrinkle resistance in cottonfabrics with strength losses less than or equal to those sustained inpresently conventional wrinkle resistance finishing processes.

The anhydrous gaseous hydrogen halide treatment is carried out atambient atmospheric pressure.

A 'wide range of temperature may be employed in carrying out thehydrogen halide treatment step of the process of this invention.Temperatures of about from 25 C. to 80 C. can be used. It is generallypreferable to conduct the hydrogen halide treatment at the lowertemperatures, from about room temperature to about 65 C., because as thetemperature of this treatment is increased, loss of strength of theproduct may become excessive if other variables of the process are notcarefully adjusted to compensate for the higher treatment temperature.

After treatment, the textile product should be thoroughly washed toremove unused reactant, residual catalyst, and byproducts. It is oftendesirable to first neutralize residual catalyst and acidic byproducts byim- Wet crease recovery angles were determined using this same procedureon samples which had been soaked for five minutes at 150 F. in watercontaining a nonionic wetting agent and blotted to remove excess 'water.

Appearance of creases.The appearance of creases before and afterlaundering was estimated by comparison with the standards of AATCCTentative Test Method 88C-1962T, pages B93-4 of the 1963 TechnicalManual of the AATCC.

Breaking strength.-This property was determined by the procedure of ASTMTest Method D1682-59T as given in ASTM Standards on Textile Materialspublished by Committee D-13 of the American Society for TestingMaterials.

Moisture regain.-AST M Test Method D629-59T was used for thedetermination of moisture regain.

The following examples are given to illustrate further the process ofthis invention.

EXAMPLE 1 Samples of the following: (i) x 80 cotton printcloth which hadbeen scoured, bleached, and desized; (ii) printcloth which had beencarboxymethylated to a D.S. of 0.11 by treatment with sodiumchloroacetate and sodium hydroxide by the process of patent application,Ser.-No. 275,169, filed Apr. 23, 1963; now abandoned; (iii printclothwhich had been carboxyethylated to .S. of 0.07 lay treatment withacrylamide and sodiu ydroxide; (iv) printcloth which had beenhydroxyethylated to a D.S. of 0.11 by treatment with ethylene oxide andsodium hydroxide; (v) printcloth hydroxyethylated similarly to a D.S. of0.15; and (vi) printcloth hydroxyethylated similarly to a D.S. of 0.21;were immersed in an aqueous solution containing 10% dimethylol ethylcarbamate, padded to about wet pickup by passing through squeeze rolls,mounted on pin frames, and dried until the fibres of the said materialscontained about their normal moisture regain value (60 C. for sevenminutes). The samples were then placed in a glass reaction chamber andtreated with 5%, based on the weight of the fabric treated (OWF), ofanhydrous hydrogen chloride gas at 42 C. for five minutes, soakedbriefly in 1% sodium carbonate solution, washed, and dried. In Table Iare shown the crease recovery angles (both conditioned and wet),breaking strengths, and moisture regains, before and after thecrosslinking treatment, and the nitrogen content of the treated samples.

TABLE I Untreated Treated Crease Recovery Crease Recovery Angle (W+F)Brk. Moisture Angle (W+F) Brk. Moisture Str. regain, N, Str. regainFabric Treated Cond., deg. Wet, deg. (W) lb. percent percent Cond., deg.Wet, deg. (W) 1b. percent Cotton 190 167 49. 7 6. 65 0. 68 261 263 29. 66. 36 Carboxymethylated Cotton, D.S.

0.11 183 49. 3 8. 44 0. 34 237 220 41. 9 8. 58 Carboxyethylated Cotton,D.S. 0.07.. 181 204 48. 9 8.10 0. 46 249 276 35. 5 8. 58Hydroxyethylated Cotton, D.S. 0.11.. 190 48.8 6.90 0.54 281 281 30. 6 6.73 Hydroxyethylated Cotton, D.S. 0.15.. 199 192 50. 6 7. 63 0. 55 297307 31. 8 6. 8 Hydroxyethylated Cotton, D.S. 0.21-. 194 195 51. 3 7. 610. 60 307 302 31. 5 7. 32

mersing the treated textile material in a dilute solution EXAMPLE 2containing sodium carbonate, sodium bicarbonate, sodium hydroxide,sodium phosphate, or the like.

Properties reported in the examples below were determined employing thefollowing test procedures:

Crease recovery angles.Determinations of conditioned crease recoveryangles (commonly called dry crease recovery angles) were carried out onsamples equilibrated at 70 F., and 65% relative humidity by the testprocedure of the American Association of Textile Chemists and Colorists,Tentative Test Method 66-1959T. This procedure is described on pages3137-8. of the 1963 Technical Manual of the AATCC (volume 39).

passing through squeeze rolls, mounted on pin frames,'-

dried at 60 C. for 7 minutes, then treated in a glass reaction chamberwith 4% O.W.F. of anhydrous gaseous hydrogen chloride at 40 C. for fiveminutes, neutralized TABLE II aqueous solution containing 10% dimethylolethyl carbamate, padded to about 85% wet pickup by passing CreaseRecovery Angle (W+F) HCHO, Finishing Agent Used Cnd., deg. Wet, deg. N.percent percent Dimethylol ethyleneurea 267 258 1. 56 2. 20 Dimethylolethyl carbamate 253 276 0. 59 2.06 Dimethylol ethyl triazone 224 252 1.35 3. 28 Met-hylated ti'irnethylol melamine 231 247 2. 78 2. 21

Tris (N-methylol-Zcarbamoylethyl) amine 278 256 1. 58 1. 95

EXAMPLE 3 15 through squeeze rolls, creased with an electric hand iron,

Samples of 80 x 80 cotton printcloth (scoured, bleached, and desized)were impregnated with 10% aqueous solutions of the following: (i)dimethylol methyl carbamate, (ii) dimethylol ethyl carbamate, (iii)dimethylol ethyleneurea, and (iv) dimethylol propyleneurea. The fabricsamples were immersed in a solution of the crosslinking agent, padded toabout 85% Wet pickup by passing through squeeze rolls, mounted on pinframes,

and ironed to dryness. The sample while creased was treated in a glassreaction chamber with O.W.F. of anhydrous hydrogen chloride at 28 C. for15 minutes, neutralized with 1% sodium carbonate solution, washed, andtumble dried. The crease was given an appearance rating of 5 bycomparison with the AATCC scale of Tentative Test Method 88C-l962T.After six repeated launderings and tumble dryings, the appearance of theTABLE IV Fabric Impregnation Hydrogen Chloride Properties of TreatedFabrics Treatment Cross Conditioned linking HCl crease agent cone.recovery Break. Moisture Crosslinking cone. percent Time, Temp, anglestrength regain agent used 1 percent 0.W F Min. C. N, percent (W+F),deg. (W) lb. percent 3 4 65 0. 56 r 257 36. 1 5.4 10 0. 5 10 65 0. 60252 35. 6 5. 3 10 0. 5 60 65 0. 71 267 27. 0 4. 6 10 10 0. 5 43 O. 59242 38. 5 6. 0 10 10 1 43 0. 68 250 34. 2 6. 4 7 4 7. 5 40 1. 01 259 30.6 6. 3 10 4 5 40 1. 31 264 35. 6 6. 8 13 2 2. 5 40 1. 71 268 31. 3 7. 27. 5 2 7. 5 4O 0. 43 258 35. 0 6. 5 7. 5 6 2. 5 40 0. 43 262 29. 9 6. 04 7. 5 0. 90 258 31. 9 6. 1 15 10 5 40 0. 93 252 26. 1 6. 3

l DMEC =dimethylol ethyl carbamate; DME U= dimethylol ethyleneurea.

TABLE III crease will still given a rating of 5 on this scale. Theappearance of the crease remained unchanged through :these repeatedlaunderings anddryings without the necessity of touch-up ironing.

Crease Recovery Angle -l-F) Break. Moisture strength regain, FinishingAgent Used N, percent Cond., deg. Wet, deg. (W) lb. percent Dimethylolmethyl carbamate 1. 19 267 265 33. 0 6. 58 Dimethylol ethyl carbainate0. 56 261 270 37. 0 6. 09 Dirnethylol ethyleneurea 1. 19 271 265 42. 26. 47 Dimethylol propyleneurea 0. 68 245 249 42. 6 6. 56

EXAMPLE 4 We claim: for im vin wrinkle resistance and Samples of 80 X 80cotton printcloth which had been 60 1 A proces pro g the scoured,bleached, and desized were impregnated with various solutions ofdimethylol ethyl carbamate or dimethylol ethyleneurea as shown in TableIV, padded to about 85 wet pickup by passing through squeeze rolls,mounted on pin frames, dried at 60 C. for seven minutes, and thentreated in a glass reaction chamber with anhydrous gaseous hydrogenchloride under various treatment conditions as detailed in Table IV.After treatment, samples were neutralized with 1% sodium carbonatesolution, washed, and 'dried. Properties of the treated samples also aregiven in the table.

EXAMPLE 5 A sample of 80 x 80 cotton printcloth which had been scoured,bleached, and desized was impregnated with an resiliency of, andimparting durable creases and washwear properties to, a chemicallymodified cotton textile material, comprising the following steps:

(a) padding the chemically modified cotton textile material selectedfrom the group consisting of carboxymethylated cotton, carboxyethylatedcotton, and hydroxyethylated cotton, with an aqueous solution containingabout from 7% to 15% by weight of dimethylol ethyl carbamate, anaminoplast creaseproofing and erosslinking agent, (b) drying the wet,impregnated chemically modified cotton textile material from (a) atabout 60 C. until the fibers of the said material contain about theirnormal moisture regain value,

9 10 (c) exposing the dry, impregnated chemically modified 2. Theprocess of claim 1 wherein the chemically modicotton textile materialfrom (b) to at least 0.5%, fied cotton textile material iscarboxymethylated cotton. based on the weight of the cotton materialtreated, 3. The process of claim 1 wherein the chemically modiofanhydrous hydrogen chloride gas catalyst, for fied cotton textilematerial is carboxyethylated cotton. periods of time about from 0.5 to60 minutes, at 5 4. The process of claim 1 wherein the chemicallymoditemperatures about from 28 to 65 C., the longer fied cotton textilematerial is hydroxyethylated cotton. periods of time being employed withthe lower temperatures to catalyze the crosslinking reaction be-References Cited tween the crosslinking chemical agent and the cellu-UNITED STATES PATENTS losic chains, and 10 O 5 6 1 h 1 (d) removing thet-hus exposed chemically modified A8 969 Rem ardt at cotton textilematerial from the hydrogen chloride V gas atmosphere, neutralizing theresidual catalyst and GEORGE LESMES Pnmary Examiner acidic byproductswith a dilute aqueous alkaline J. CANNON, Assistant Examiner solution,and water washing and drying the resulting T 5 crosslinked chemicallymodified cellulosic cotton material to remove unused reactants, residualcata- 8--115.6; 38--144 lyst, and byproducts.

